Applications of laser-processed substrate for molecular diagnostics

Abstract

Surface enhanced Raman Scattering (SERS) and related modalities offer greatly enhanced sensitivity and selectivity for detection of molecular species through the excitation of plasmon modes and their coupling to molecular vibrational modes. One of the chief obstacles to widespread application is the availability of suitable nanostructured materials that exhibit strong enhancement of Raman scattering, are inexpensive to fabricate, and are reproducible. I describe nanostructured surfaces for SERS and other photonic sensing that use semiconductor and metal surfaces fabricated using femtosecond laser processing. A noble metal film (e.g., silver or gold) is evaporated onto the resulting nanostructured surfaces for use as a substrate for SERS. These surfaces are inexpensive to produce and can have their statistical properties precisely tailored by varying the laser processing. Surfaces can be readily micropatterned and both stochastic and self-organized structures can be fabricated. This material has application to a variety of genomic, proteomic, and biosensing applications including label free applications including binding detection. Using this material, monolithic or arrayed substrates can be designed. Substrates for cell culture and microlabs incorporating microfluidics and electrochemical processing can be fabricated as well. Laser processing can be used to form channels in the substrate or a material sandwiched onto it in order to introduce reagents and drive chemical reactions. The substrate can be fabricated so application of an electric potential enables separation of materials by electrophoresis or electro-osmosis.

Description

REFERENCE TO PENDING PRIOR PATENT APPLICATION[0001]This patent application claims benefit of pending prior U.S. Patent Application Ser. No. 60 / 690,385, filed Jun. 14, 2005 by Steven M. Ebstein for APPLICATIONS OF LASER-PROCESSED SUBSTRATE FOR MOLECULAR DIAGNOSTICS, which patent application is hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention pertains to an apparatus and a method for quantitatively detecting and distinguishing between compounds, especially biomolecules, with high sensitivity and selectivity using a laser-processed substrate and an optical source and detector.BACKGROUND OF THE INVENTION[0003]Molecular diagnostics are an increasingly important part of biotechnology. The ability to detect small quantities of genomic, proteomic, and other biological materials enables sensitive clinical tests to be performed, as well as enabling laboratory research that affects drug development and functional biology. Molecular sensing modalities in...

AI Technical Summary

Problems solved by technology

While current technology is quite useful, it is not as sensitive or as specific as is desired, and there is room for improvement in the speed and economics of the diagnostics.

The utility of many current genomic assays is limited by the need to replicate sample material using techniques like Polymerase Chain Reaction (PCR), which can add noise, take time to process, and may add cost through royalty payments.

One barrier to the use of Raman spectroscopy is the small cross-section for Raman scattering, a factor of ˜1014 less than the cross-section for fluorescence.

However, it is generally acknowledged that detailed knowledge and prediction of the surface enhancement phenomenon is not completely understood at this time.

Those substrates were particularly unpredictable and often changed their properties over time due to electrochemical reactions.

Another substrate with interesting properties, but which is probably not affordably manufacturable, is e-beam lithography of silicon.

One major reason often cited in the literature is the lack of availability of a suitable substrate material.

Other substrates are expensive or difficult to prepare.

While some of the SERS substrates I have described above meet one or more of these criteria, no substrate is currently commercially available that meets all of them.

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